The present invention relates to data storage and retrieval systems, and in its most commercially important form has a heat-producing imaging means which images a heat-responsive recording medium in alpha-numeric, pictorial or digitally coded patterns.
In its most sophisticated form, the present invention uniquely provides at a data processing station, preferably equipped with a typewriter-like keyboard, control means for providing a dry process, human and machine readable microfilm record, with add-on capabilities, of said image patterns from digital or analog electrical data input signals either originating externally of the data processing station or generated, for example, by depression of the keys of the typewriter-like keyboard. The control means provide for a selection of sizes of the alpha-numeric character or picture-forming images formed on a microfiche card or other recording medium. Thus, the control means selectively can produce full-sized alpha-numeric title-forming images on a title-receiving portion of a microfiche card, so that the subject matter of the microfiche card can be directly viewed by the operator, or minutely-sized images on a selected frame of the microfiche card. Full-sized images can also be recorded simultaneously with the recording of the minutely-sized images on a recording medium, which may be a heat-responsive medium like that of the microfiche card or on paper. These images duplicate the data recorded on the microfiche card, so that recorded data can be directly read by the operator or by one desiring immediately to use the information without the use of microfilm projection means, or can be sent as or like hard copy to others by mail or otherwise. By operating still other control means, analog electrical signals representing medical X-ray or other pictorial data are received, processed and fed to the imaging means to record the same in greatly reduced size on the frames of a microfiche card or other recording mediums. Other control means enable the operator to directly view data previously recorded on a selected microfiche card frame by conventional light projection or other means, or uniquely to generate electrical signals directly from the images on a selected microfiche card frame which can operate conventional remote display devices.
One of the most important applications of the present invention is as a replacement for present mechanical typewriters used in offices and the like, where it is desired to eliminate completely the need for initially preparing letters, reports, and the like on paper for office record purposes. In the present invention, the operation of alpha-numeric character producing keys produces microfilm records directly or by transfer from buffer storage to dry process-developed microfiche cards or the like, where alpha-numeric character reductions of as much as 24 to 1 and greater are achieved. As previously indicated, if a hard copy is desired for mailing or the like, simultaneously with the production of the microfilm records a duplicate hard copy is produced on a typewriter or other printing device. There is thus no necessity for keeping paper records of any kind since all initially prepared letters, data records, reports etc. are produced on microfiche cards or the like. Additionally, data can be added at any time to any point of a microfiche frame on which data was not previously recorded, unlike typical wet processed developed microfilm.
An important specific aspect of the invention, which greatly facilitates the commercialization of the invention, is the use of a uniquely micro-sized heating head as the imaging means which by joule heating produces micro-sized data on a heat-responsive recording medium having archival properties to produce a high packing density of dot images producing a practically non-destructible record. Where digital coded data is recorded by such means, the resultant record can replace presently available flexible disc, tape cartridge, and other similar magnetic data storage media used in computer systems and the like, wherein the stored data deteriorates with age, with substantial cost savings. The heating head has at least one and preferably a number of current-carrying points each having dimensions preferably no greater than about 14 micron and less desirably no greater than about 20 micron to produce a similarly sized dot image in the recording medium (assuming a short current pulse rather than DC is fed to each point). A continuous or DC current may be fed to each point where pictures or curves rather than alpha-numeric characters are being recorded, provided the heating head is moved along the recording medium at speed preventing undue spreading of the heat.
Printers have been heretofore developed using heating heads to record on paper record media, the heads comprising a matrix or linear array of current-carrying segments which receive current which generates heat within the segments by Joule (current) heating conducted to, or sparks or current in, an adjacent paper recording medium, to create an image therein of alpha-numeric characters of about the same size produced by the type of conventional typewriters or a picture or curve of a size directly visible discernible, but it was not appreciated by those having knowledge of these printers that Joule heat sources could be miniaturized and used to form micro-sized dot images in a heat-responsive recording film to produce as much as 24 to 1 and greater reductions of alpha-numeric or correspondingly reduced picture images therein which can be readily viewed by conventional microfilm projection techniques. Thus, it is believed that U.S. Pat. No. 3,599,228, U.S. Pat. No. 3,852,563 U.S. Pat. No. 3,862,394 and U.S. Pat. No. 3,903,393 disclose heat-applying printing heads which can produce only oridinary type-sized alpha-numeric images or readily directly visible pictures. U.S. Pat. Nos. 3,852,563 and 3,599,228 each disclose rows and columns of current-carrying heat generating points which, because of the configuration comprising large numbers of orthogonally related conductors makes it extremely difficult if not impossible to achieve imaging capable of producing microform reductions of the order of magnitude of 24 to 1. While U.S. Pat. No. 3,852,563 discloses integrated circuit structures, since the integrated circuit diodes must pass appreciable amounts of current, the resulting diode sizes as well as the conductor configuration make the heating head unsuitable for producing the substantial image reductions as referred to. U.S. Pat. No. 3,862,394 shows a heat applying head with resistance wire supported within spaced grooves in a wire positioning bar, and U.S. Pat. No. 3,903,393 discloses a heat applying head formed by the deposition of thick resistive films, and these heads are also impractical for producing reductions of the degree required for microfilm records.
The heat applying heads preferably utilized in the invention are capable of producing 24 to 1 and greater reduced microfilm records like that produced by laser beams heretofore moved over heat-responsive recording media which absorb the laser beam energy to produce transparent or opaque images therein. However, the use of laser beam energy for this purpose requires very expensive, bulky, and inefficient equipment. For example, efficiencies of laser beam energy source suitable for producing microfilm records like that achieved by the present invention commonly operate with efficiencies less than 1 percent. In such case, the power supplies required to supply the needed amount of energy are very expensive and large in size. An additional problem with laser beam energy sources is that the present OSHA specifications do not permit the use of laser beam sources in such environments as business offices and the like. In contrast, Joule heat producing sources operate at relatively high efficiencies from compact and relatively inexpensive power sources and are useable in all environments.
While, Joules heating may be produced within the recording medium by the flow of current between very small current-carrying conductors of the heat applying head and the recording medium, micro-sized images are best achieved by using in the heat applying head a linear array of closely spaced current-carrying resistance-forming points which form micro-sized heating points. In one form of the invention, the resistance-forming points are formed by thin film deposits of resistive material, from spaced portions of which extend individual low resistance conductors. In another form of the invention, a linear array of resistance-forming points are formed from very thin filaments of juxtaposed resistance wires coated with a thin film of insulating material, and having aligned V-shaped portions formed by stretching the same over the feathered edge of an insulating substrate, with the pointed ends thereof remaining exposed. The substrate and filaments of resistance wires are formed into a monolithic body by potting the same in a synthetic plastic material. The exposed ends of the V-shaped portions of the filaments of resistance wire are so very closely spaced and the deposited film resistance-forming points referred to each occupy such a very small area (having dimensions preferably no greater than about 14 micron and less desirably no greater than about 20 micron) that up to 9 or 10 such current-carrying heat generating points can encompass a length less than about 200 micron, and so can generate by selective energization thereof as the heating heads described are advanced along a recording medium alpha-numeric characters of a size reduction of the order of at least about 24 to 1.
The nature of the heat-responsive recording medium is also important in the production of micro-sized images. Practically all of the heat-responsive recording media heretofore utilized by the aforementioned printers using heating heads are unsuitable for producing micro-sized images. In the first place, these recording media comprise heat sensitive coatings applied over or impregnated into the fibers of a paper substrate. The thicknesses of the coating utilized and the rough texture of the substrate were generally such that images of the small sizes produced by the present invention are not producible therein. Also, these recording media do not produce a pattern of transparent and opaque areas, so that the information recorded thereon cannot be read by projecting visible light therethrough to produce the most easily readable magnified images, as do the most desirable recording media.
For most of the applications of the present invention, the recording medium comprises a solid transparent substrate of a suitable synthetic plastic material, like Mylar, upon which is coated a film of heat-responsive imaging material of thicknesses generally less than about 0.2 micron. To protect the imaging film material from wear during handling it is generally desirable to apply a protective coating thereover. The overall thickness between the outer surface of the protective coating and the inner surface of the imaging film next to the substrate should preferably not be much more than about 0.5 micron and less desirably not much greater than about 2 micron, to avoid the undesired spreading of the heat therein which could cause image sizes much greater than the size of the current-carrying points of the heat applying head utilized in the present invention. Film thicknesses are of particular importance where visible images are to be projected upon a viewing screen and the imaging material is initially opaque and is rendered transparent by the application of heat thereto. In such case, for the transparent area to permeate completely the thickness of the film of imaging material, the heat must extend through the entire thickness thereof. Since the heat spreads in all directions through the film, overall film thicknesses in excess of about 2 micron would increase the size of the image produced so that the image resolutions achieveable are inadequate to produce sharp magnified images for alpha-numeric data reductions of the order of magnitude of about 24 to 1 and greater.
While the present invention could utilize initially transparent films, like the diazo-type, vesicular-type, or dry silver-type films, modified to be insensitive to light and highly sensitive to heat, and resettable amorphous chalcogenide films disclosed in U.S. Pat. No. 3,530,441 and organio-metallic films like that disclosed in U.S. application Ser. No. 596,646, 596,617 and 596,616 all filed July 17, 1970, when they are utilized with appropriate small thicknesses as described, the preferred type of recording medium is the initially opaque type of films disclosed in U.S. application Ser. No. 577,003, filed May 13, 1975. The preferred film applied to the substantially transparent substrate is a solid high optical density and substantially opaque film of a dispersion imaging material, which upon application thereto of Joule heat energy above a certain critical value, changes to a substantially fluid state in which the surface tension of the material acts to cause a substantially opaque film subjected to the heat energy to disperse and change to a discontinuous film comprising openings and deformed material which are frozen in place following the application of the heat energy. Generally, the openings occupy a much greater area then the deformed material over the region heated by a single heat producing point of the heat producing head so that when light projected through this region of the film it appears like substantially the entire area thereof is transparent.
When it is desired to produce an image having a varying degree of transparency, to produce X-ray films or pictures with a gray scale variation in the recording medium, then the film is similar to that just described except that the film of imaging material includes means for retarding the change in the discontinuous film caused by surface tension and for controlling the amount of such change in accordance with the intensity of the applied heat energy above the critical value, so that the optical density of the film varies in accordance with the intensity of the heat energy applied thereto above the critical value.
In the most preferred form of the invention, the heating head is mounted on a support which preferably continuously scans a frame of the microfiche card or other recording medium on a line-by-line format, as in the case of an electron beam scanning the face of a cathode ray tube, so that an entire frame of a microfiche card can be recorded with the alpha-numeric information in about a few seconds or less. In such case, the microfiche card is indexed only to bring a record starting point of a selected frame opposite the heating head prior to the start of a heating head scanning operation. The relatively light-in-weight heating head can be moved at high scanning speeds not practical, for example, if the microfiche card support frame were to be moved relative to the heating head in the X and/or Y axis directions.
Electrical signals can be generated from the recording medium most advantageously by the use of an electrical readout head which scans a light projected image by moving the microfiche card or other recording medium relative to light responsive elements of the electrical readout head or by moving the reading head relative to the recording medium. However, it is preferred to mount the electrical readout head on the same or support frame similar to that which carries the heating head, so that the electrical readout head scans in a line-by-line progression the entire frame of information involved at high scanning speeds. In such case, the readout head most preferably comprises a number of optical filaments of a size and spaced like the current-carrying points of the above described micro-sized heating head. While full-sized printed matter has been scanned by a spot of light reflected upon a photocell to produce electrical signals fed to facsimile recorders, it has not been appreciated that microfilm recorded data could be directly machine readable as just described.
The above described and other features and advantages of the invention will become more apparent upon making reference to the specifications to follow, the drawings and the claims.